Download The Respiratory System

The Respiratory System
What are the
primary functions of
the respiratory system?
Oxygen
• Is obtained from the air by diffusion
across delicate exchange surfaces of
lungs
• Is carried to cells by the cardiovascular
system which also returns carbon
dioxide to the lungs
5 Functions of the
Respiratory System
1. Provides extensive gas exchange
surface area between air and
circulating blood
2. Moves air to and from exchange
surfaces of lungs
5 Functions of the
Respiratory System
3. Protects respiratory surfaces from
outside environment
4. Produces sounds-speaking, singing
5. Participates in olfactory sense
Components of the Respiratory System
Figure 23–1
Organization of the
Respiratory System
• The respiratory system is divided into
the upper respiratory system, above
the larynx, and the lower respiratory
system, from the larynx down
The Respiratory Tract
• Consists of a conducting portion:
– from nasal cavity to terminal bronchioles
• Consists of a respiratory portion:
– the respiratory bronchioles and alveoli Are air-filled pockets within the lungs
• where all gas exchange takes place
The Respiratory Epithelium
Figure 23–2
Alveolar sac
Alveoli
Figure 23–2
The Respiratory Epithelium
• For gases to exchange efficiently:
– alveoli walls must be very thin (< 1 µm)
– surface area must be very great (about 35
times the surface area of the body)
The Respiratory Mucosa
• Consists of:
– an epithelial layer
– an areolar layer
• Lines conducting portion of respiratory
system
The Lamina Propria
• Underlies areolar tissue
• In the upper respiratory system, trachea, and
bronchi:
– contains mucous glands that secrete onto
epithelial surface
• In the conducting portion of lower respiratory
system:
– contains smooth muscle cells that encircle lumen
of bronchioles
How are delicate
respiratory exchange surfaces
protected from pathogens,
debris, and other hazards?
The Respiratory Defense System
• Consists of a series of filtration
mechanisms
• Removes particles and pathogens
Components of the Respiratory
Defense System (1 of 2)
• Goblet cells and mucous glands:
– produce mucus that bathes exposed
surfaces
• Cilia:
– sweep debris trapped in mucus toward the
pharynx (mucus escalator)
Components of the Respiratory
Defense System (2 of 2)
• Filtration in nasal cavity removes large
particles
• Alveolar macrophages engulf small
particles that reach lungs
What are the organs of the
upper respiratory system and
their functions?
The Upper Respiratory System
Figure 23–3
The Nose
• Air enters the respiratory system:
– through nostrils or external nares
– into nasal vestibule
• Nasal hairs:
– are in nasal vestibule
– are the first particle filtration system
The Nasal Cavity
• The nasal septum:
– divides nasal cavity into left and right
• Mucous secretions from paranasal sinus
and tears:
– clean and moisten the nasal cavity
• Superior portion of nasal cavity is the
olfactory region:
– provides sense of smell
• From vestibule
to internal
nares:
– through
superior,
middle, and
inferior
meatuses
Air Flow
Meatuses
• Constricted
passageways that
produce air
turbulence:
– warm and
humidify incoming
air
– trap particles
The Palates
• Hard palate:
– forms floor of
nasal cavity
– separates nasal
and oral cavities
• Soft palate:
– extends posterior
to hard palate
– divides superior
nasopharynx from
lower pharynx
The Nasal Mucosa
• Warm and
humidify inhaled
air for arrival at
lower respiratory
organs
• Breathing
through mouth
bypasses this
important step
The Pharynx
• A chamber shared
by digestive and
respiratory
systems
• Extends from
internal nares to
entrances to
larynx and
esophagus
Divisions of the Pharynx
• Nasopharynx
• Oropharynx
• Laryngopharynx
The Nasopharynx
• Superior portion
of the pharynx
• Contains
pharyngeal tonsils
and openings to
left and right
auditory tubes
The Oropharynx
• Middle portion of
the pharynx
• Communicates
with oral cavity
The
Laryngopharynx
• Inferior portion of
the pharynx
• Extends from
hyoid bone to
entrance to
larynx and
esophagus
What is the structure
of the larynx and its
role in normal breathing
and production of sound?
Anatomy of the Larynx
Figure 23–4
Cartilages of the Larynx
• 3 large, unpaired
cartilages form the
larynx:
– the thyroid cartilage
– the cricoid cartilage
– the epiglottis
The Thyroid Cartilage
• Also called the Adam’s
apple
• Is a hyaline cartilage
• Forms anterior and
lateral walls of larynx
• Ligaments attach to
hyoid bone, epiglottis,
and laryngeal
cartilages
The Cricoid
Cartilage
• Is a hyaline
cartilage
• Form posterior
portion of larynx
• Ligaments attach
to first tracheal
cartilage
• Articulates with
arytenoid
cartilages
The Epiglottis
• Composed of
elastic
cartilage
• Ligaments
attach to
thyroid
cartilage and
hyoid bone
Cartilage Functions
• Prevents entry of food and liquids into
respiratory tract
– During swallowing:
– the larynx is elevated
– the epiglottis folds back over glottis
• Thyroid and cricoid cartilages support and
protect:
– the glottis
– the entrance to trachea
The Glottis
Figure 23–5
Sound Production
• Air passing through glottis:
– vibrates vocal folds
– produces sound waves
Sound Variation
• Sound is varied by:
– tension on vocal folds
– voluntary muscles (position arytenoid cartilage
relative to thyroid cartilage)
Speech
• Is produced by:
– phonation:
• sound production at the larynx
– articulation:
• modification of sound by other structures
What is the structure of
airways outside the lungs?
Anatomy of the Trachea
Figure 23–6
The Trachea
• Also called the
windpipe
• Extends from
the cricoid
cartilage into
mediastinum
– where it
branches into
right and left
pulmonary
bronchi
The Tracheal Cartilages
• 15–20 tracheal cartilages:
– strengthen and protect airway
– discontinuous where trachea contacts
esophagus
• Ends of each tracheal cartilage are
connected by:
– an elastic ligament and trachealis muscle
The Primary Bronchi
• Right and left primary bronchi:
– separated by an internal ridge (the carina)
The Right Primary Bronchus
• Is larger in diameter than the left
• Descends at a steeper angle
Structure of Primary Bronchi
• Each primary bronchus:
– travels to a groove (hilus) along medial
surface of the lung
Hilus
• Where pulmonary nerves, blood vessels, and
lymphatics enter lung
• Anchored in meshwork of connective tissue
What are the superficial
anatomy of the lungs, the
structure of a pulmonary
lobule, and the functional
anatomy of the alveoli?
Gross Anatomy of the Lungs
Figure 23–7
The Lungs
• Left and right
lungs:
– are in left and
right pleural
cavities
• The base:
– inferior portion of
each lung rests on
superior surface
of diaphragm
The Right Lung
• Has 3 lobes:
– superior,
middle, and
inferior
– separated by
horizontal and
oblique fissures
The Left Lung
• Has 2 lobes:
– superior and
inferior
– are separated
by an oblique
fissure
Relationship between Lungs and Heart
Figure 23–8
Lung Shape
• Right lung:
– is wider
– is displaced upward by liver
• Left lung:
– is longer
– is displaced leftward by the heart forming
the cardiac notch
The Bronchial Tree
• Is formed by the primary bronchi and their
branches
Extrapulmonary Bronchi
• The left and right bronchi branches outside
the lungs
Intrapulmonary Bronchi
• Branches within the lungs
A Primary Bronchus
• Branches to form secondary bronchi (lobar
bronchi)
• 1 secondary bronchus goes to each lobe
Bronchi and Lobules
Figure 23–9
Secondary Bronchi
• Branch to form
tertiary bronchi,
also called the
segmental bronchi
• Each segmental
bronchus:
– supplies air to a
single
bronchopulmonary
segment
Bronchial
Structure
• The walls of
primary, secondary,
and tertiary
bronchi:
– contain
progressively less
cartilage and more
smooth muscle
– increasing muscular
effects on airway
constriction and
resistance
Bronchitis
• Inflammation of bronchial walls:
– causes constriction and breathing
difficulty
The Bronchioles
Figure 23–10
Bronchiole Structure
• Bronchioles:
– have no cartilage
– are dominated by smooth muscle
Autonomic Control
• Regulates smooth muscle:
– controls diameter of bronchioles
– controls airflow and resistance in lungs
Bronchodilation
• Dilation of bronchial airways
• Caused by sympathetic ANS activation
• Reduces resistance
Bronchoconstriction
• Constricts bronchi
• Caused by:
– parasympathetic ANS activation
– histamine release (allergic reactions)
Asthma
• Excessive stimulation and bronchoconstriction
• Stimulation severely restricts airflow
Trabeculae
• Fibrous connective tissue partitions from root
of lung
• Contain supportive tissues and lymphatic
vessels
• Branch repeatedly
• Divide lobes into increasingly smaller
compartments
Pulmonary Lobules
• Are the smallest compartments of the lung
• Are divided by the smallest trabecular
partitions (interlobular septa)
Surfaces of the Lungs
• Each terminal bronchiole delivers air to a
single pulmonary lobule
• Each pulmonary lobule is supplied by
pulmonary arteries and veins
Exchange Surfaces
• Within the lobule:
– each terminal bronchiole branches to form several
respiratory bronchioles, where gas exchange takes
place
The Bronchioles
• Each tertiary
bronchus branches
into multiple
bronchioles
• Bronchioles
branch into
terminal
bronchioles:
– 1 tertiary
bronchus forms
about 6500
terminal
bronchioles
Alveolar Organization
Figure 23–11
Alveolar
Organization
• Respiratory
bronchioles are
connected to
alveoli along
alveolar ducts
• Alveolar ducts
end at alveolar
sacs:
– common
chambers
connected to
many individual
alveoli
An Alveolus
• Has an
extensive
network of
capillaries
• Is
surrounded
by elastic
fibers
Alveolar
Epithelium
• Consists of simple
squamous
epithelium
• Consists of thin,
delicate Type I cells
• Patrolled by
alveolar
macrophages, also
called dust cells
• Contains septal cells
(Type II cells) that
produce surfactant
Surfactant
• Is an oily
secretion
• Contains
phospholipids and
proteins
• Coats alveolar
surfaces and
reduces surface
tension
Respiratory Membrane
• The thin membrane of alveoli where gas
exchange takes place
3 Parts of the
Respiratory Membrane
1. Squamous epithelial lining of alveolus
2. Endothelial cells lining an adjacent capillary
3. Fused basal laminae between alveolar and
endothelial cells
Inflammation of Lobules
• Also called pneumonia:
– causes fluid to leak into alveoli
– compromises function of respiratory
membrane
Pleural Cavities and Pleural Membranes
Figure 23–8
Pleural Cavities and
Pleural Membranes
• 2 pleural cavities:
– are separated by the mediastinum
• Each pleural cavity:
– holds a lung
– is lined with a serous membrane (the
pleura)
The Pleura
• Consists of 2 layers:
– parietal pleura
– visceral pleura
• Pleural fluid:
– lubricates space between 2 layers
Respiration
• Refers to 2 integrated processes:
– external respiration
– internal respiration
External Respiration
• Includes all processes involved in exchanging
O2 and CO2 with the environment
Internal Respiration
• Also called cellular respiration
• Involves the uptake of O2 and production of
CO2 within individual cells
3 Processes of
External Respiration
1. Pulmonary ventilation (breathing)
2. Gas diffusion:
–
across membranes and capillaries
3. Transport of O2 and CO2:
–
–
between alveolar capillaries
between capillary beds in other tissues
What physical principles govern the
movement
of air into the lungs?
Pulmonary Ventilation
• Is the physical movement of air in and
out of respiratory tract
• Provides alveolar ventilation
Gas Pressure and Volume
Figure 23–13
Atmospheric Pressure
• The weight of air:
– has several important physiological effects
Boyle’s Law
• Defines the relationship between gas pressure
and volume:
• As volume decreases, pressure increases
• In a contained gas:
– external pressure forces molecules closer together
– movement of gas molecules exerts pressure on
container
Mechanisms of Pulmonary Ventilation
Figure 23–14
Respiration
• Causes volume changes that create
changes in pressure
• Volume of thoracic cavity changes:
– with expansion or contraction of
diaphragm or rib cage
The Respiratory Muscles
Figure 23–16a, b
The Respiratory Muscles
Figure 23–16c, d
3 Muscle Groups of Inhalation
1. Diaphragm:
–
–
contraction draws air into lungs
75% of normal air movement
2. External intracostal muscles:
–
–
assist inhalation
25% of normal air movement
3. Accessory muscles assist in elevating
ribs:
–
–
–
–
sternocleidomastoid
serratus anterior
pectoralis minor
scalene muscles
Changes in Respiratory
System at Birth (1 of 5)
1. Before birth:
–
–
pulmonary vessels are collapsed
lungs contain no air
2. During delivery:
–
placental connection is lost
–
blood PO falls
–
PCO rises
2
2
3. At birth:
–
newborn overcomes force of surface tension to
inflate bronchial tree and alveoli and take first
breath
Changes in Respiratory
System at Birth (4 of 5)
4. Large drop in pressure at first breath:
–
–
–
pulls blood into pulmonary circulation
closing foramen ovale and ductus arteriosus
redirecting fetal blood circulation patterns
5. Subsequent breaths:
–
fully inflate alveoli
Respiratory Performance and Age
Figure 23–28
3 Effects of Aging on the Respiratory System
1. Elastic tissues deteriorate:
–
–
reducing lung compliance
lowering vital capacity
2. Arthritic changes:
–
–
restrict chest movements
limit respiratory minute volume
3. Emphysema:
–
–
affects individuals over age 50
depending on exposure to respiratory
irritants (e.g., cigarette smoke)